The euro is heading to parity with the dollar — and soon, according to analysts at Goldman Sachs.

The euro dropped back below $1.06 for the first time in half a year yesterday, and it's been weakening from about $1.13 in early October.

A lot of analysts got excited about the euro reaching $1 early this year, immediately after the European Central Bank (ECB) introduced a larger-than-expected quantitative easing programme. Though the euro appreciated in value over the summer, Goldman's...